PHP 4.0 Bug #6913: wrong use of C language, serious bug!
| From: | melchers at cis dot fu-berlin dot de | Date: | Thu, 28 Sep 2000 01:47:32 +0000 |
| Subject: | PHP 4.0 Bug #6913: wrong use of C language, serious bug! | ||
| Groups: | php.dev | ||
| Request: | Send a blank email to php-dev+get-33749@lists.php.net to get a copy of this message | ||
From: melchers@cis.fu-berlin.de
Operating system: IRIX-6.x
PHP version: 4.0.2
PHP Bug Type: Sockets related
Bug description: wrong use of C language, serious bug!
file ext/standard/file.c contains the line:
if ((*buf = FP_FGETC(socketd, (FILE*)what, issock)) == EOF) {
this is a _serious_ bug, since on _all_ machine architectures where the data type
"char" defaults to unsigned, the return value of FP_FGETC() is converted to
unsigned, before it is compared to EOF. Since EOF is defined as (-1), the
comparison _never_ succedds. This makes any usage of sockets and file-I/O
on "unsigned char" architectures impossible. As far as i remember, the bug
occurs in all php versions, i.e. 3.x and 4.x.
my page for fgetc(3) says:
WARNING
If the integer value returned by getc, getchar, or fgetc is stored into a
character variable and then compared against the integer constant EOF,
the comparison may never succeed, because sign-extension of a character
on widening to integer is machine-dependent.